Two days of finals to go, only one that features Michael Phelps and Ryan Lochte - and both have built an eight-event programme, one less solid than the other but only in terms of the potential medal count.

Phelps looks set to repeat his Beijing 2008 pursuit of eight, while Lochte is less certain to play a role in medley and sprint freestyle relays, the latter leaning on what happens in the butterfly final tomorrow.

Not quite an exact match but the magnitude of the head-to-head is unprecedented in swimming history: the clash is nowhere more direct than in three solo events, while the mirror image of the distances to be covered by both men (up to 3,300m of gruelling battle) at London 2012 will be warped only by the rate of progress each one manages through rounds and the hit rate each man manages as far as getting into the relay finals.

Phelps' chance of a repeat of 2008 are lengthened by the blooming of Ryan Lochte and even more so, perhaps, by the might of the Australian 4x100m freestyle relay. The US went into Beijing best on paper in 2008 in the sprint relay with France a threat. Gaul galloped ahead early on but the US managed to get back on top. This time the Americans are genuinely the underdog and even if you're pessimistic about the Dolphins and optimistic for the Stars and Stripes, the gap is significant.

After an epic day that left both men feeling and looking drained, Phelps, looking forward to having a 27th birthday dinner with his family and acknowledging just how tired he felt, was gracious enough to note what was obvious to all: Lochte, just 0.09sec away, had done even more - a 1:54.54 200 back in a blistering battle with Tyler Clary just half an hour before the medley, followed by qualification in a fast butterfly field, all within an hour. Ask any world-class swimmer you like: a stunning undertaking.

Gators head coach and US head men's coach come the hour, Gregg Troy described Lochte's efforts as "probably the best performance I haver ever seen from him". A monumental moment - and while defeat stings under any circumstances, there were rewards down the line in what was achieved today (for both men).

"You're definitely in a lot of pain if you do 3 events in an hour," said Phelps, a multi-eventer who has faced his own fast-repeat challenges down the years. "Starting off with the 200 back, that's very tough on the legs, especially long-course and Tyler got in there and raced hard. I would never stand up for it. I did it eight years ago. I'm glad I don't have to do that again. The lactic acid does build up. He's tough and he raced three challenging races and he did them well."

Asked about his rivalry, he told the media "It's great … you guys are gonna get the answer you always get" before adding: "Neither one of us wants to lose and when we get in the water we always raced really hard. Whether we race cat and mouse, we're going all out. They are fun races. Ryan has proved he's been the best the last couple of years. Ryan is the world record holder in the 200IM and getting in water with him is something I like and am looking forward to is [in London 2012]."

In Omaha, Phelps has managed to defeat Lochte in both events in which he was beaten by Lochte in Shanghai at world titles a year ago. Not the same measure, of course. Victory at trials, Phelps noted, "doesn't really matter … The bigger races are a couple of weeks down the road. Trials for the Americans are much more stressful than the Games are … I'm looking forward to getting home and relaxing and getting back into it [training]. I'm looking forward to it. I have some things I want to finish my career with and Bob [Bowman, coach at Baltimore] and I are going to try to perfect those."

Lochte, asked why he raced the 100 butterfly, said: "Tonight was probably the most pain I’ve endured in a swimming competition. Going back-to-back-to-back was definitely hard, but, you know, I was up for the challenge. It’s something that I’ve been training for the past four years, so I knew I was able to do it. And the 100 fly, it was just, I guess, a different event - an event I’ve never done before." Yes, he added, he would swim the final tomorrow.

What had he learned about himself this week, he was asked. "I’m used to racing against him [Phelps]. I’ve been doing it for eight years now," said Lochte. "He’s one of the toughest competitors out there. The past four years I’ve gone a lot faster, and I know what my body can handle. And I know this meet was just, I guess, stepping stones for what I really want to do in London. Overall, I’m pretty happy with how the meet is going. I still have one more race tomorrow, so I guess we’ll just have to wait and see how the 100 fly goes, and then, you know what, just get ready for London.

Given that Ryosuke Irie is ahead of him on the 200m world rankings, was he satisfied with the backstroke? "Irie’s really fast. I’ve been racing against him for a couple of years now, and I know what he’s capable of doing. The time that I went tonight is irrelevant. It doesn’t really matter about the time. It just matters about getting your hand on the wall. I mean, that’s what I had to do, but I can tell you this much, that come London I’m going to have to put in a better performance in order to win."

What had been the hardest part of the triple event? "I guess just being able to get up and racing the top people in the world and racing them all the way to the finish," said Lochte. "It’s one of the hardest things to do because that first event, 200 backstroke - if you’re a backstroker, anyone can tell you it’s one of the hardest events out there. It just takes your legs out of you. And then being able to come back like 20 minutes later, going against Michael Phelps, I knew I was up for the challenge. It was definitely hard. I’m a little tired, but I guess it’s good for you."

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The US London 2012 qualifiers after six days

Men

100m freestyle: Nathan Adrian 48.10; Cullen Jones 48.46

200m freestyle: Michael Phelps 1:45.70; Ryan Lochte 1:45.74

400m freestyle: Peter Vanderkaay, 3:47.67, Conor Dwyer, 3:47.83

100m backstroke: Matt Grevers, 52.08 WTB; Nick Thoman, 52.86

200m backstroke: Ryan Lochte, 1:54.54; Tyler Clary, 1:54.88

100m breaststroke: Brendan Hansen, 59.68; Eric Shanteau, 1:00.15

200m breaststroke: Scott Weltz, 2:09.01; Clark Burckle 2:09.97

200m butterfly: Michael Phelps, 1:53.65; Tyler Clary, 1:55.12

200m medley: Michael Phelps, 1:54.84; Ryan Lochte, 1:54.93

400 medley: Ryan Lochte, 4:07.06; Michael Phelps 4:07.89 (Phelps becomes the first American male swimmer to make it to four Olympic Games)